This invention relates to photosensitive members of recording apparatus, and more particularly it is concerned with a photosensitive member in the form of an endless belt which is constituted into a unit together with a plurality of rollers supporting and driving it.
In one type of recording apparatus, a photosensitive member in the form of an endless belt is trained over a drive wheel, a tension roller and a support roller, with the drive roller driving the photosensitive member in the form of an endless belt while a suitable tension is being imparted to the photosensitive member by the tension roller.
Generally, a photosensitive member in the form of an endless belt would suffer the disadvantage that it would deteriorate with time due to fatigue, and when this happens, the old photosensitive member should be replaced by a new one. When replacements of the photosensitive member are performed, it has hitherto been usual practice to remove the old photosensitive member in the form of an endless belt from the rollers over which it is trained before a new one is trained over them.
This operation of attaching and detaching the new and old photosensitive members is troublesome and time-consuming, and involves the risk that the hand of an operator might inadvertently touch the surface of the photosensitive member, thereby damaging same.
To obviate this problem, proposals have been made to form the photosensitive member into a unit together with the rollers for supporting and driving it, so that the photosensitive member can be replaced by a new one together with the rollers which form a unit therewith, without having to go to the trouble of detaching and attaching the rollers. This facilitates replacing the old photosensitive member with a new one, thereby improving operability of photosensitive member replacing.
If the photosensitive member in the form of an endless belt were replaced as a unit together with the rollers, a new photosensitive member in the form of an endless belt would be stored in reserve as a unit with the rollers for supporting and driving it. As a result, the photosensitive member would be tensioned while it is being stored in spite of the fact that tensioning the photosensitive member in the form of an endless belt can wait until it is mounted to a recording apparatus. The rollers for supporting and driving a photosensitive member in the form of an endless belt are usually small in diameter. Thus, if the photosensitive member were tensioned while being stored before it is mounted to a recording apparatus, the photosensitive member might be kept in a condition in which it is bent at a sharp angle for a prolonged period of time. The result of this would be that the endless belt would be permanently bent in certain portions. When the photosensitive member in the form of an endless belt that is deformed like this is mounted to a recording apparatus to perform recording of information, images produced on recording sheets would be poor in quality due to improper resolution caused by a floating movement of the photosensitive member in an exposing section, a variation in density from one image to another due to non-uniform charging, and faulty transfer-printing due to non-uniform superposing of transfer-printing sheets on the photosensitive member.